JP6429939B1 - Idle speed control device for internal combustion engine - Google Patents

Abstract

An idling speed control device that eliminates fluctuations in engine speed and engine stall caused by brake operation is obtained. In an internal combustion engine that uses an intake negative pressure of an engine as a boosting source of a brake, an engine speed is controlled to a target speed by adjusting an intake air amount with an electronic throttle 5 by PI control. 1 rotation speed feedback control means 8a, and second rotation speed feedback control means 8b for controlling the engine speed to the target speed by adjusting the ignition timing to advance or retard by P control, When the engine is in an idle state and a brake operation is detected, the lower limit value is switched so that the amount of operation on the reduction side on the first rotation speed feedback control means is reduced, and the amount of reduction on the first rotation speed feedback control means is reduced. When the side operation amount reaches the lower limit value, the P control by the second rotation speed feedback control means is switched to the PI control. [Selection] Figure 1

Description

  The present invention relates to an idling engine speed control device for an internal combustion engine, and more particularly to an idling engine speed control device for an internal combustion engine in which the intake negative pressure of the engine is used as a brake boosting source.

In order to reduce the operating force of the brake pedal of a vehicle, a brake booster (master bag) device that uses the suction negative pressure of the engine as a boost source of a vacuum servo brake and boosts the operating force is employed.
As shown in FIG. 5, such a brake booster includes a constant pressure chamber 151 into which negative pressure is introduced from the engine, and a variable pressure chamber 152 into which air is introduced. When the brake pedal 18 is not operated, it is in a negative pressure state where the introduction of the atmosphere into the variable pressure chamber 152 is blocked, and the constant pressure chamber 151 and the variable pressure chamber 152 are in communication. Next, when the brake pedal 18 is operated, the constant pressure chamber 151 and the variable pressure chamber 152 are blocked by the valve plunger 153, and the atmosphere is introduced into the variable pressure chamber 152, whereby the constant pressure chamber 151, the variable pressure chamber 152, The pressure difference causes a boosting action, and the operating force of the brake pedal 18 is reduced.

In an internal combustion engine equipped with the above-described brake booster and an idle speed control device (ISC) that controls the engine speed during idling to a target speed, when the brake pedal operation is repeated during idle speed control, the brake booster Since air flows into the intake manifold, there is a problem that idle speed control is affected and the engine speed fluctuates.
Equipped with an idle speed control device (ISC = idle speed control) that can control the idle speed to the target speed, and suppresses fluctuations in the engine speed due to air returned from the brake booster to the intake manifold when the brake pedal is operated As such, there is one disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2002-106396).

  The apparatus disclosed in Patent Document 1 includes control means that can control the idle speed to a target speed by controlling the opening and closing of the ISC valve, and includes a linkage between the brake pedal position displacement detection means, the master bag, and the intake manifold. A one-way valve provided in the middle of the communication passage, and a one-way valve operation detecting means for detecting an operation state of the one-way valve, and the one-way valve operation detecting means controls the operation of the one-way valve. When detected, the ISC control of the ISC valve is stopped or the feedback correction width of the ISC control of the ISC valve is set to the minimum level during the operation of the one-way valve and until the predetermined time has elapsed after the end of the operation of the one-way valve. A function to control as much as possible is added to the control means.

  Also, a brake pedal position displacement amount detection means is provided, and when the displacement amount detected by the brake pedal position displacement amount detection means is larger than a preset determination value, the ISC control of the ISC valve is stopped, or the ISC valve A function for controlling the feedback correction width of the ISC control to the minimum level is added to the control means, and the increase in the intake flow rate when the brake pedal is operated is restricted from being reduced by the ISC. Proposals have been made to prevent problems such as rotation drop and engine stall at the moment when the supply of the engine stops.

JP 2002-106396 A

  In the idling engine speed control device for an internal combustion engine, as shown in FIG. 6, when the brake operation is switched from on to off or from off to on, air flows from the master bag into the intake manifold, thereby increasing the engine speed Ne. There is a case. If the rotation feedback control is performed in such a state, the control is performed in the direction of reducing (decreasing) the air amount. There is a problem that, as indicated by NG in FIG. 6, rotation drop or engine stall occurs at the moment when the supply of air from the master bag stops when the amount of air is reduced by ISC control.

  As a measure for preventing the rotation drop and the engine stall failure, there is a method of stopping the rotation feedback control which is one of the functions of the ISC control when the brake is operated. Stopping the engine speed feedback control during brake operation eliminates the engine stall or engine speed drop, but the engine speed increases due to the inflow of air from the master bag. Further, since the brake operation and the inflow of air from the master bag do not necessarily match, the ISC control is unnecessarily stopped when there is no air inflow during the brake operation, and the control accuracy of the target rotational speed control during idling is lowered. There is a case. In addition, installing a detection means for detecting air inflow from the master bag leads to an increase in cost.

In the configuration described in Patent Document 1, as shown in FIG. 7, when the air inflow from the master bag by the brake operation exceeds a predetermined amount, the engine speed Ne is set to increase the intake negative pressure. As a result, the engine speed Ne increases when the brake is applied, resulting in an unnecessary engine operating state. Therefore, although the driver is decelerating, as the engine speed Ne increases as indicated by NG in FIG. 7, the driver feels uncomfortable.
In the case of an automatic transmission, the creeping force increases as the engine speed Ne increases, and the braking distance will be different from the driving sensation unless the brake operation is taken care of. .

  The present invention has been made to solve the above-described problems, and is an internal combustion engine that eliminates a driver's uncomfortable feeling due to fluctuations in engine speed, engine stall, and engine speed increase associated with braking operation in an idle state. It is an object of the present invention to provide an engine idle speed control device.

An idle speed control device for an internal combustion engine according to the present invention comprises a brake operation detecting means for detecting an on / off state of a brake pedal and an electronic throttle for controlling an intake air amount supplied to the engine. In an internal combustion engine in which the intake negative pressure of the engine is used as a boosting source, the intake air amount is adjusted by the electronic throttle by PI control according to the difference between the target engine speed and the actual engine speed, The first rotation speed feedback control means for controlling the engine speed to the target speed, and the ignition timing is adjusted to advance or retard by P control according to the difference between the target speed and the actual speed. controls by the Fourier engine rotational speed to the target rotation speed, a second rotational speed feedback control means capable of switching the P control to the PI control, the engine is idle , When executed by the first and second rotational speed feedback control means, if the brake operation detecting means detects the brake-on operation, the lower limit as reduced side operation amount of the first rotational speed feedback control means decreases When the limit value is switched and the reduction side manipulated variable in the first rotation speed feedback control means becomes the lower limit limit value, the ignition timing control by the second rotation speed feedback control means is changed from P control to PI control. It is to be switched.

According to the present invention, by the reduction side operation amount limitation by the first rotational speed Fordback control means during the brake operation, without using the detection means for detecting the air inflow from the brake booster (master bag) to the intake manifold, A certain amount of air inflow from the brake booster (master bag) to the intake manifold can be detected, and the amount of control of the first rotational speed Fordback control is limited more than usual so that the intake air can be maintained even after the brake is not operated. The amount of air flowing into the manifold can be secured, and a drop in engine speed and engine stall can be avoided.
Further, after the correction amount by the first rotational speed Fordback control means reaches the lower limit value, the ignition timing control by the second rotational speed feedback control means is performed, thereby suppressing an increase in the rotational speed of the engine. It is possible to suppress the uncomfortable feeling of driving feeling and the uncomfortable feeling of braking and driving feeling due to an increase in creep force.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a vehicle internal combustion engine that includes an internal combustion engine idle speed control device according to Embodiment 1 of the present invention; It is a flowchart for control of the idle speed control device in Embodiment 1 of this invention. It is a flowchart for determination of a brake device. It is a time chart figure of the idle speed control apparatus and ignition control apparatus in Embodiment 1 of this invention. It is a schematic block diagram of a general brake booster (master bag). FIG. 7 is a time chart when a stall occurs during deceleration (stop) with brake on, which is a problem of the present invention. It is a time chart figure of the idle speed control apparatus shown by the prior art.

Embodiment 1 FIG.
Hereinafter, an idling engine speed control device for an internal combustion engine according to Embodiment 1 of the present invention will be described with reference to FIGS.
1 is a schematic configuration diagram of an internal combustion engine (engine) for a vehicle including an internal combustion engine idle speed control apparatus according to Embodiment 1 of the present invention.

An internal combustion engine (engine) 1 has an electronic throttle 5 that adjusts the amount of air flowing into an intake pipe 4 as an intake manifold, a surge tank 14 that suppresses intake pulsation, and an air / fuel ratio that is optimum for the air that flows in as an intake system. A fuel injection valve (injector) 10 for injecting fuel and an ignition plug 3 for combusting an air-fuel mixture sucked into the combustion chamber 2 through the intake port 9 are provided, and an exhaust pipe 11 is used as an exhaust system. Is provided with a catalyst 13 for reducing harmful substances from the combustion gas.
The electronic throttle 5 includes an electronic throttle motor 7 that controls the opening and closing of the throttle valve to adjust the amount of intake air by the electronic throttle 5.

Further, the surge tank 14 is provided with a negative pressure line 16 connected to a brake booster (master bag) 15 as shown in FIG. 5, and a one-way valve 17 is provided in the middle of the negative pressure line 16. Yes. When the brake pedal 18 is depressed, negative pressure is drawn from the constant pressure chamber 151 of the brake booster 15, and the operating force of the brake pedal 18 is reduced by a boosting action due to the pressure difference between the constant pressure chamber 151 and the variable pressure chamber 152.
A brake switch 18a that outputs a brake signal k is provided in conjunction with the operation of the brake pedal 18, and the brake switch 18a functions as a brake operation detection means that detects the on / off state of the brake pedal 18. To do.

As an electronic control system, an electronic control device 8 is provided for controlling the amount of air flowing into the intake pipe 4, the amount of fuel ejected from the fuel injection valve 10, the ignition timing of the spark plug 3, and the like. The device 8 is also provided with an idle speed control device.
For this reason, the electronic throttle 5 detects the throttle valve opening and outputs the throttle opening signal d, and the throttle opening sensor 22 outputs the throttle opening signal d. The intake pipe 4 detects the intake pressure of the surge tank 14 and outputs the intake pressure signal a. An intake pressure sensor 19 that detects the coolant temperature of the engine 1 and outputs a water temperature signal e; a crank angle sensor 20 that detects rotation of the crankshaft and outputs a crank angle signal b to the crankshaft; A rotational speed sensor 21 that detects the engine rotational speed and outputs a rotational speed signal c, and the exhaust pipe 11 includes an O2 sensor 12 that detects the oxygen concentration in the combustion gas and outputs an oxygen concentration signal f. Yes.

The input unit 8 c of the electronic control device 8 inputs these signals a to f and k, and outputs an output signal g to the electronic throttle motor 7, an output signal h to the fuel injection valve 10, and a spark plug 3. The engine control is performed by outputting the ignition signal m and the like from the output unit 8d of the electronic control unit 8.
When idling (stopping without operating the accelerator pedal), feedback control by P (proportional) I (integral) control according to the deviation between the target rotational speed calculated from the water temperature signal e and the actual rotational speed calculated from the crank angle signal b , The signal g is output to the electronic throttle motor 7 to control the opening of the electronic throttle 5 to adjust the intake air amount. Hereinafter, this control is referred to as first rotation speed feedback control, and is executed by the first rotation speed feedback control means 8a of the electronic control device 8.
Further, the ignition signal m is output to the spark plug 3 by feedback control based on P (proportional) control according to the deviation between the target rotational speed and the actual rotational speed, and the ignition timing is adjusted to advance or retard. Hereinafter, this control is referred to as second rotation speed feedback control, and is executed by the second rotation speed feedback control means 8b of the electronic control unit 8.

FIG. 2 is a flowchart showing a correction amount calculation process of the rotational speed feedback control as a control flowchart for the idle rotational speed control device.
First, in step S101, it is determined whether or not the flag during brake operation is “1”. The brake operation flag “1” refers to a state in which the brake switch 18a is ON for a predetermined time or longer and is set for a predetermined time after the brake switch 18a is OFF in the flow process of FIG.

In step S101, if the brake operation flag is “1” (YES), the lower limit value is switched so that the reduction-side operation amount by the first rotation speed feedback control becomes small in step S102. That is, the lower limit value of feedback control is added. In step S101, if the brake operation flag is not “1” (NO), switching of the lower limit value for reducing the reduction-side operation amount by the first rotation speed feedback control is canceled in step S103. That is, the addition of the lower limit value of the feedback control is canceled. In step S104, the correction amount by the first rotation speed feedback control is calculated.
Here, the correction amount of the feedback control is controlled (clipped) so as not to be below the lower limit value.

Next, in step S105, it is determined whether or not the flag during brake operation is “1”. If the brake operating flag is “1” in step S105 (YES), it is determined whether the correction amount by the first rotational speed feedback control calculated in step S104 in step S106 is the lower limit value. .
If the correction amount by the first rotational speed feedback control is the lower limit value in step S106 (YES), the second rotational speed feedback control is switched from P control to PI control in step S107, and step S109. To calculate the correction amount of the second rotational speed feedback control.

  In step S106, when the correction amount by the first rotation speed feedback control calculated in step S104 is not the lower limit value (NO), the correction amount of the second rotation speed feedback control by P control in step S109. Is calculated. In step S105, when the brake operating flag is “0” (NO), in step S108, the second rotation speed feedback control is switched to P control, and the I value is reset.

  FIG. 3 shows a process for determining whether or not a brake operation for switching the rotational speed feedback control is being performed. First, in step S201, it is determined whether the ON state of the brake switch 18a continues for a predetermined time. If the brake switch 18a has continued for a predetermined time or longer (YES), the brake operation flag is set to “1” in step S202, In step S203, a brake operating flag release timer is set. This is to prevent frequent switching and release of the rotational speed feedback lower limit value in the case of, for example, stepping on the brake pedal 18 or pumping brake.

Here, the release timer set in step S203 is a timer that always performs a subtraction process at a constant interval. When the release timer set process is not performed, the subtraction is continued until it becomes “0” at a constant interval.
If the brake switch 18a is OFF in step S201 or has not been ON for a predetermined time (NO), it is determined in step S204 whether or not the brake operation flag release timer is “0”. If yes (YES), the brake operating flag is cleared in step S205.
With the above processing, the brake switch 18a serving as the brake operation detecting means detects that the brake pedal 18 is on and that the brake pedal 18 is being operated for a predetermined time after the brake pedal 18 is turned off.

FIG. 4 is a time chart diagram of the idle speed control device and the ignition control device according to Embodiment 1 of the present invention, and the first speed feedback control means when the brake switch 18a is turned on when the engine is in an idle state. The control state by 8a and the 2nd rotation speed feedback control means 8b is shown.
As shown in FIG. 4, when the brake operation is detected when the engine is in an idling state, the lower limit value is switched so that the amount of operation on the reduction side at the first rotational speed feedback control means 8a becomes smaller than when the brake is not operated. . When the manipulated variable by the first rotational speed feedback control means 8a reaches the lower limit value, the second rotational speed feedback control means 8b for adjusting the ignition timing is switched from P control to PI control, and the engine speed increases. (Torque UP) suppression is performed from air amount control to ignition timing control.
As a result, even if the engine speed Ne rises due to the inflow of air from the brake booster (master bag) 15, the engine speed increase (torque UP) is suppressed from the air amount control to the ignition timing control. As shown by OK of 4, an increase in the engine speed Ne is suppressed, and the driving feeling does not become uncomfortable.

  As described above, according to the present invention, when the brake operation is detected when the engine is in the idling state, the intake air amount is increased / decreased by the electronic throttle 5 by PI control according to the difference between the target rotation speed and the actual rotation speed. The lower limit value is switched so that the operation amount on the reduction side in the first rotation speed feedback control means 8a becomes smaller than that when the brake is not operated. Further, when the operation amount by the first rotational speed feedback control means 8a becomes the lower limit limit value during the brake operation, it is determined that the amount of air flowing from the brake booster 15 into the intake pipe 4 as the intake manifold is large, The second rotational speed feedback control means 8b for adjusting the ignition timing to advance or retard so as to eliminate the rotational deviation according to the difference between the target rotational speed and the actual rotational speed is switched from P control to PI control, and the engine speed Suppression (torque UP) suppression is performed from air amount control to ignition timing control.

Thereby, it is possible to prevent the air amount from being excessively reduced by the first rotation speed feedback control means 8a during the brake operation, and it is also possible to suppress the rotation increase by the second rotation speed feedback control means 8b.
Further, since there is a delay time between the on / off operation of the brake pedal 18 and the variation in the amount of air flowing in from the brake booster 15, the brake operation is performed for a predetermined time while the brake pedal 18 is on and after the brake pedal is turned off. Detects as inside. As a result, control failure due to a delay in the inflow air amount when the brake is off can be suppressed.
Switching of the lower limit value of the decrease side operation amount of the first rotation speed feedback control means 8a is performed only during the brake operation.

The PI control of the second rotation speed feedback control means 8b is performed when the brake is being operated and the operation amount by the first rotation speed feedback control means 8a becomes the lower limit value.
When the brake operation is changed from being operated to non-operating, the switching of the lower limit value for reducing the operation amount on the reduction side in the first rotation speed feedback control means 8a is canceled, and the first rotation speed feedback control is performed. The lower limit value of the means 8a is returned to the original value, the second rotational speed feedback control means 8b is switched from PI control to P control, and the integral term of the control value of the second rotational speed feedback control means 8b is reset. .
Thereby, even when the inflow air amount from the brake booster 15 at the time of brake-off is lost, the fall of rotation speed can be suppressed.

  According to such an idle speed control device, a constant air inflow from the brake booster 15 to the intake manifold can be performed without using a device such as a sensor for detecting the amount of air flowing from the brake booster 15 to the intake manifold. It can be detected. Since excessive control of the first rotational speed feedback control means 8a due to the amount of air flowing in from the brake booster 15 at the time of brake on / off operation can be suppressed, rotational fluctuations due to brake operation, engine stall, and rotation increase during brake operation The driver's uncomfortable feeling can be resolved.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and various design changes can be made. Within the scope of the present invention, each embodiment is described. These embodiments can be freely combined, and each embodiment can be modified or omitted as appropriate.

1: engine, 2: combustion chamber, 3: spark plug, 4: intake pipe (intake manifold),
5: Electronic throttle, 7: Throttle motor, 8: Electronic control unit, 8a: First rotational speed feedback control means, 8b: Second rotational speed feedback control means,
10: Fuel injection valve, 12: O2 sensor, 15: Brake booster (master bag),
18: Brake pedal, 18a: Brake switch (brake operation detecting means)

Claims (4)

An internal combustion engine having brake operation detecting means for detecting the on / off state of the brake pedal and an electronic throttle for controlling the amount of intake air supplied to the engine, and using the intake negative pressure of the engine as a brake boost source In the engine, the engine speed is controlled to the target speed by adjusting the intake air amount by the electronic throttle by PI control according to the difference between the target speed and the actual speed of the engine. of the rotational speed feedback control means, in accordance with the difference between the target speed and the actual rotation speed, the target rotation speed Fourier engine rotational speed by the adjusting advancing and retarding the ignition timing by the P control And a second rotation speed feedback control means capable of switching the P control to PI control .
When the engine is in an idle state and the brake operation detection means detects a brake- on operation during execution by the first and second rotation speed feedback control means, the weight reduction by the first rotation speed feedback control means When the lower limit value is switched so that the side operation amount becomes smaller and the reduction side operation amount in the first rotation speed feedback control means becomes the lower limit value, the second rotation speed feedback control means An idling speed control device for an internal combustion engine, wherein the ignition timing control is switched from P control to PI control. Wherein the brake operation detecting means, the brake pedal after a predetermined time has elapsed turned on from off, the brake pedal from ON to Do Ri predetermined time off, characterized by detecting the in brake-on operation Item 2. The idle speed control device for an internal combustion engine according to Item 1. When the brake- on operation by the brake operation detecting unit is not operated from being operated, the switching of the lower limit value for reducing the amount of decrease-side operation in the first rotation speed feedback control unit is canceled, 3. The idle speed control device for an internal combustion engine according to claim 1, wherein the lower limit limit value by the first speed feedback control means is returned to the original value. When the brake- on operation by the brake operation detecting means is changed from being operated to non-operating, the control is switched from the PI control by the second rotational speed feedback control means to the P control, and the control by the second rotational speed feedback control means. 3. The idle speed control device for an internal combustion engine according to claim 1, wherein the integral term of the value is reset.

Images